Chronometer (general definition)
In order for a movement to be worthy of the name "chronometer", it has to endure fifteen days of merciless testing, responsibility for which has been entrusted to the famous Contrôle Officiel Suisse des Chronomètres (COSC).
According to the definition generally accepted in watchmaking circles, "a chronometer is a high-precision watch displaying seconds whose movement has been tested over a period of several days, in different positions and at different temperatures, by an official neutral body. Movements that have satisfied the criteria for precision set by ISO 3159 standard are issued with an official chronometer certificate."
A chronometer should therefore not be confused with a chronograph, even though a chronograph is used to measure time, and even though the word chronometer is frequently - and mistakenly - used to describe an "instrument for measuring duration". A chronograph can be certified as a chronometer so long as it meets the criteria set by the standard, but not all chronometers are chronographs.
For want of a rival, the only "official neutral body" qualified in Switzerland to award the title of "chronometer" is the famous COSC, founded in 1973 and still operating from the same facilities. The COSC is a "non-profit association" created by five Swiss watchmaking cantons (Bern, Geneva, Neuch‚tel, Soleure and Vaud) with the Federation of the Swiss Watch Industry (FH). In its three "Official Bureaux" (laboratories) at Biel, Geneva and Le Locle, highly sophisticated and secret equipment developed by its own engineers is used by the COSC to test the accuracy of each movement submitted to it by manufacturers.
Each movement is tested in five positions and at three different temperatures (8∞C, 23∞C, 38∞C) over a period of fifteen days. To qualify for the chronometer certificate, a movement must satisfy seven criteria relating to aspects such as mean daily rate, difference in rate between vertical and horizontal positions, and precision according to temperature variation. The minimum requirements specify that the "rate variation" must be less than 4/+6 seconds per day (for movements greater than 20 mm in diameter).
Each chronometer is identified by a number engraved on the movement and by a COSC certificate number.
Based on ISO 3159, the COSC has also drawn up a set of testing standards applicable to quartz chronometers. Each movement is tested for eleven days, in one position and at three temperatures. In addition, it is subjected to 3-dimensional rotations and to 200 shocks equivalent to 100 G (100 times stronger than gravity) for an entire day.
To be awarded the chronometer certificate, a quartz movement must satisfy eight qualifying criteria. The minimum requirements for accuracy are naturally much higher than in the case of mechanical movements.
Manufacturers have therefore been forced to develop movements fitted with an electronic system which compensates for the frequency variation of quartz according to temperature changes (thermocompensated movements).
Whether mechanical movements or quartz movements, only the most robust calibres will receive the much-acclaimed COSC certification.
To put it plainly, the official chronometer certificate means that a movement meets the highest standards of precision and reliability. It is only awarded to those movements assembled using superior quality components and in accordance with the most stringent timing criteria.
The fact remains nevertheless that the COSC tests are static tests conducted in a laboratory, and are not the same as a wearing simulation test. Nor indeed is the complete watch tested for water resistance or robustness as only the movement, not the cased-up watch, undergoes testing.
The chronometer certificate comes at a price, however. In addition to the fees payable to the COSC (it is estimated that the various brands pay around 30 euros for each movement submitted), manufacturers who submit their movements for certification cannot afford to submit standard calibres which would stand no chance of passing the current tests. As a result, the movements submitted have been lavished with attention at the numerous manufacturing and assembly stages, and this additional cost, though difficult to quantify, is estimated to run to several hundreds of euros depending on the type and number of movements.
On the other hand, the chronometer certificate serves as a superb selling point for the brands. Armed with this official document, the timepiece appreciates in value and so attracts a higher price. The fact that fewer than 3% of the watches produced in Switzerland are awarded the chronometer certificate each year shows the extent to which this piece of paper is synonymous with quality and exclusivity. The first to grasp this was Rolex whose history is inextricably linked with that of the COSC.
Indeed, since 1910, the mythical Genevan brand has entrusted the bulk of its movements to chronometer certification. For Rolex, the chronometer certificate is a pledge of quality and consistency. By relying for nearly a century on the quality and rigour of the services provided by the COSC, the brand has effectively become its backbone as the organisation is heavily reliant for its income on the contributions made by Rolex.
For brands who manufacture or assemble their own movements, the qualitative leap towards COSC certification is not straightforward; the development and manufacture of movements worthy of being COSC-certified require major resources in terms of production facilities, not to mention a raft of watchmaking skills needed behind the scenes.
The honours list of "COSC-certified" brands
According to the latest available figures, the Contrôle Officiel Suisse des Chronomètres (COSC) certified 1,271,934 watch movements in 2002, up 0.5% compared with 2001. Although the certification of over one million chronometers each year may seem considerable, it actually represents only a tiny percentage of world watch production.
Rolex, the heavyweight of Swiss watchmaking, ranks first in the category of companies awarded the largest number of chronometer certificates.
In 2002, 584,665 certificates were awarded to movements produced by Manufacture Rolex SA of Biel, while 230,055 certificates were awarded to those produced by Montres Rolex SA of Geneva, in other words a total of 814,720 COSC-certified timepieces (compared with 762,175 in 2001), meaning that Rolex was awarded two-thirds of all certificates issued by the prestigious Swiss body.
In second place is Omega with 165,543 certificates issued in 2002, followed by Breitling (131,815), Panerai (39,016), TAG Heuer (20,207), Baume & Mercier (15,504), Bulgari (11,141), Corum (8,005), Chopard (7,684) and Tissot (6,221).
Le Figaro / Michel Jeannot